The present invention deals with a medical treatment device. While conceivably the device could be utilized in the context of a variety of body spaces, the present description, for the sake of brevity, will be focused primarily on the treatment of vascular aneurysms. Accordingly, the present invention deals with an aneurysm treatment device for at least partially obstructing the neck portion of a vascular aneurysm.
A vascular aneurysm can be described as a localized stretching or distension of an artery due to a weakening of the vessel wall. The vascular distension itself is often referred to as an aneurysm sac and is typically related to a defect in the muscular coating of the artery and is probably developmental in origin. The entrance area that leads from the vessel to the aneurysm sack is often referred as an aneurysm neck. Often an aneurysm can be the site of internal bleeding and, catastrophically, the site of a stroke.
Several methods of treating aneurysms have been attempted, with varying degrees of success. At present, the treatment of aneurysms with drugs is substantially ineffective. Also, extra-vascular surgery, referred to as open craniotomy, for the purpose of preserving the parent artery is replete with disadvantages. A patient subject to open craniotomy for intercranial aneurysms typically must undergo general anesthesia, surgical removal of part of the skull, brain retraction, dissection around the neck of the aneurysm sac, and placement of a clip on the parent artery to prevent bleeding or rebleeding.
Alternative treatments include endovascular occlusion where the interior of the aneurysm is entered with a guidewire or a microcatheter. An occlusion is formed within the sac with an intention to preserve the parent artery. One means for forming the occlusion is through the introduction of an embolic agent within the sac. Examples of embolic agents include detachable coils, which are detached from the end of a guidewire, liquid polymers that polymerize rapidly on contact with blood to form a firm mass, and embolic particles delivered through a catheter.
Endovascular occlusion is not without drawbacks. For example, there is a risk of overfilling the sac and consequent embolic agent migration into the parent vessel. Overfilling of the sac can also generate undesirable additional pressure in the aneurysm.
Aneurysms that have a particularly wide opening between the aneurysm sac and the parent vessel (xe2x80x9cwide neck aneurysmxe2x80x9d) present difficulties concerning the retention of embolic materials. Specifically, wide neck aneurysms make it very difficult to maintain embolics (or other occlusive materials) within the aneurysm sac. This is especially true of liquid embolic materials. Of course, should the embolic material enter the parent vessel, it poses an undesirable risk of occlusion in the parent vessel.
Another means for forming a mass in an aneurysm sac involves the placement of an elastic expandable balloon in the aneurysm. Detachable occlusion balloons have been used for a number of medical procedures. These balloons are typically carried at the end of a catheter and, once inflated, are detached from the catheter. Such a balloon may be positioned within an aneurysm, filled and then detached from the catheter. Deploying the balloon within the aneurysm can be rather difficult due to the high rates of blood flow through the aneurysm.
In addition to delivery complications, elastic balloons have exhibited other problems with respect to performance in the context of vascular aneurysms. For example, as the balloon is inflated within an aneurysm, the operator must be very careful not to overfill the balloon due to possible risk of rupturing the aneurysm. Accordingly, following inflation, the balloon may be too small, potentially resulting in a release of the balloon from the aneurysm into the blood stream. Furthermore, the balloon often does not mold or shape to the odd-shaped contours of the aneurysm, leaving room for blood to continue flowing through the aneurysm, or generating undesired pressure on the aneurysm walls.
Another means for treating vascualr aneurysms involves the placement of a liner in the aneurysm sac. An aneurysm liner includes a liner sac that is placed in the aneurysm sac and filled so as to occlude the aneurysm. A guidewire is typically utilized to carry the liner through the vasculature and to assist in deploying the liner in the aneurysm.
While the aneurysm liner concept is intuitively attractive, it has posed a number of technical challenges. One primary challenge involves the difficulty in producing a material that is robust enough to contain embolic material without inhibiting the ability of the embolics to conform to the aneurysm geometry itself, rather than the geometry of the liner. In many instances, materials currently incorporated into aneurysm liner concepts are not compliant enough to adequately remodel the neck portion of an aneurysm sac. This disadvantage can lead to neck remnants and subsequently recanalization after embolization.
Most current aneurysm liners are physically inconvenient or inappropriate for treatment of large aneurysms. For example, many liner concepts involve forming the aneurysm liner of a woven or braided polymeric material such as polypropylene or polyester. These mesh materials are difficult to use in treating medium to large size aneurysms, for example, aneurysms 5-20 millimeters in diameter. Such mesh materials result in an assembly that is too bulky when collapsed down into the catheter for delivery. In other words, the amount of liner material required to fill a relatively large aneurysm is very difficult to collapse down into a constrained, low profile, delivery configuration small enough to be delivered and deployed without excess friction on the walls of the delivery catheter or other delivery lumen. The bulkiness of these devices makes them inconvenient or inappropriate for intra-cranial delivery.
It should also be noted that many current aneurysm liner concepts lack consistent and effective expansion systems or concepts. A consistent and effective expansion reduces procedural complications associated with transformation of liners from a constrained state in a delivery catheter to an unconstrained state when deployed in an aneurysm.
The present invention is an aneurysm treatment device for treating aneurysms of various shapes and sizes.
One aspect of the present invention pertains to an implantable medical device for at least partially closing a neck portion of a vascular aneurysm. The treatment device includes a collapsible neck bridge having a delivery configuration and a deployed configuration. The treatment device also includes an actuation mechanism operably attached to the collapsible neck bridge and configured to covert the collapsible neck bridge between the delivery configuration, wherein the actuation mechanism has an elongated form, and the deployed configuration, wherein the actuation mechanism has a constricted form.
Another aspect of the present invention pertains to a method of treating an aneurysm in a parent vessel having a lumen, the aneurysm having a neck and inner wall defining a cavity that is in communication with the lumen. The method includes a step of providing a collapsible neck bridge that incorporates an actuation mechanism and is detachably connected to a distal end of an elongated delivery member. The method includes endovascularly moving the collapsible neck bridge in a delivery configuration, wherein the actuation mechanism has an elongated form, to a site proximate the aneurysm. The method also includes actuating the actuation mechanism so as to convert the collapsible neck bridge from the delivery configuration to a deployed configuration, wherein the actuation mechanism has a constricted form.
Yet another aspect of the present invention pertains to a system for treating an aneurysm in a vessel, the aneurysm having an inner wall and a neck defining a cavity. The system includes an elongated delivery member, and a treatment device disconnectably attached to the elongated delivery member. The treatment device comprises a collapsible beck bridge that incorporates a constrictable actuation mechanism that has an elongated form and a constricted form. The collapsible neck bridge takes a delivery configuration when the actuation mechanism is in the elongated form. The collapsible neck bridge takes a deployed configuration when the actuation mechanism is in the constricted form.